Delaminatable containers are conventionally known that include a container body having an outer shell and an inner bag and having the inner bag delaminating, with a decrease in contents, from the outer shell to be shrunk, and a check valve to regulate entrance and exit of air between an external space of the container body and an intermediate space between the outer shell and the inner bag (PTLs 1 and 2). In addition, delaminatable containers are conventionally known that inhibits entrance of air inside the container by delaminating, with a decrease in contents, the inner layer from the outer layer to be shrunk (PTL 3). Such a delaminatable container is provided with an inner bag composed of an inner layer and an outer shell composed of an outer layer.
In PTL 1, a cap mounted to the mouth of the container body has a built-in valve.
In PTL 2, inside the main portion of the outer shell is equipped with a valve.
In PTL 3, the presence of holes in the inner bag is inspected based on whether a pressure in the inner bag reaches a predetermined value at a predetermined time after air is supplied into the inner bag.